Formaldehyde-based resins or formaldehyde-containing resins, such as urea-formaldehyde (UF) resins, phenol-formaldehyde (PF) resins, including PF resins extended with urea (PFU), melamine-formaldehyde (MF) resins, melamine-formaldehyde resins modified with urea (MUF) and the like, find widespread use as adhesives, bonding agents and strengthening agents for making a wide variety of products.
For example, PF and PUF resins in particular have been the mainstays of fiberglass insulation binder technology over the past several years. Such resins are inexpensive and provide cured fiberglass insulation products with excellent physical properties.
Such formaldehyde-base resins, particularly, MF, MUF and UF resins, have been used as binders in acoustical tiles, e.g., ceiling tiles, and PF and MF resins have been used to impregnate or saturate thin fibrous, usually cellulosic, e.g., paper, sheets which are assembled in layers and cured to form protective, decorative laminates.
Formaldehyde itself, or compositions based on formaldehyde or which emit formaldehyde also have long been used to provide permanent press, or wrinkle free characteristics to textiles. Representative of this technology are U.S. Pat. Nos. 6,827,746; 5,885,303; 4,396,390 and 4,108,598.
Rigid but friable foams made from PF and UF resins also are widely used to provide water to cut flowers. These commercially available floral foams usually are formulated as an open-celled, cured PF resin, and have the capability of retaining a significant amount of moisture.
The ability of these formaldehyde-based compositions to provide the necessary performance benefits at a reduced cost relative to other technologies has thus made such formaldehyde-based compositions, including UF, PF, MF, MUF and PUF resins, popular in connection with the preparation of a variety of products that find their way into commercial and residential uses.
One of the drawbacks of using formaldehyde-based compositions in such applications, however, is the potential for formaldehyde emissions from the finished article. It is known that gaseous formaldehyde is released from such articles, some of which is attributable to unreacted formaldehyde in the cured resin binder and some of which may be attributable to degradation or decomposition products generated over time under acidic conditions, elevated temperatures, and/or high humidity from components of the articles.
Thus, there is a continuing need for new methods for reducing formaldehyde emission in products produced using formaldehyde-based or formaldehyde containing compositions.